Rosette Calcium Carbonate Undercoat for Heat Discoloration
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Solution Overview
Problem
Thermosensitive recording media face challenges in maintaining heat discoloration resistance, especially in the blank portions, under high temperature conditions.
Innovation Solution
Incorporating a rosette type precipitated calcium carbonate with spindle-shaped primary particles aggregated radially to form secondary particles in the undercoat layer, and limiting its bulk density to 240 g/L or less, effectively hampers heat transfer and improves heat discoloration resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pigments and binders are used in the undercoat layer, then the manufacturing process is simple, but the heat discoloration resistance in blank portions is insufficient under high temperature conditions
Solution Approach 1:
The patent changes the physical parameters of the pigment particles by specifying a bulk density of 240 g/L or less, which corresponds to a specific particle size range (0.5-5 μm). This parameter change optimizes the heat insulating properties of the undercoat layer, improving heat discoloration resistance without requiring complex compositional changes
Solution Approach 2:
The patent creates a composite undercoat layer structure by combining specific pigments (precipitated calcium carbonate with bulk density ≤240 g/L) and binders (polyvinyl alcohol and carboxymethyl cellulose sodium). This composite material approach achieves superior heat discoloration resistance through synergistic effects of the selected components
2Loss of energy
If the undercoat layer uses materials with high heat insulation properties, then heat transfer is reduced and heat discoloration resistance improves, but the selection and processing of materials becomes more complex
Solution Approach 1:
The patent specifies a bulk density parameter of 240 g/L or less for the pigment, which directly controls the particle size and packing density. This parameter optimization achieves effective heat insulation while maintaining ease of manufacture, as the specified parameter range corresponds to commercially available precipitated calcium carbonate products
Solution Approach 2:
The patent utilizes the porous structure inherent in precipitated calcium carbonate particles with bulk density ≤240 g/L. The porous nature of these particles provides air pockets that enhance heat insulation properties, reducing heat transfer to the thermosensitive recording layer while keeping the material selection straightforward
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly enhances the heat discoloration resistance of thermosensitive recording media, particularly in the blank portions, by reducing heat transfer and improving the absorbing properties of the undercoat layer.
Implementation Method 1
the undercoat layer containing such a pigment hampers the heat transfer from the support to the thermosensitive recording layer effectively, which is considered to improve the heat discoloration resistance of the thermosensitive recording medium by reducing the heat transfer
Implementation Method 2
the undercoat layer is considered to absorb the color developing material contained in the thermosensitive recording layer, especially the excess color developing agents that are not involved in the chemical reaction with the leuco dye
Data Source
Figure 1~2
AI summary
The objective of the present invention is to provide a thermosensitive recording having an excellent heat discoloration resistance, especially an excellent heat discoloration resistance in the blank portions. Provided is a thermosensitive recording medium comprising (i) a support, (ii) an undercoat layer installed on the support comprising a pigment and a binder as main components, and (iii) a thermosensitive recording layer installed on the undercoat layer comprising a colorless or pale colored electron donating leuco dye and an electron accepting color developing agent as main components, wherein the pigment contained in the undercoat layer is a rosette type precipitated calcium carbonate comprising spindle-shaped primary particles aggregated radially to form secondary particles, and the bulk density of the rosette type precipitated calcium carbonate is 240 g/L or less.